DeMarse, T. B., Killeen, P. R., & Baker, D. (1999).
Satiation, capacity, and within-session responding.
Journal of the Experimental Analysis of Behavior,
72, 407-423.
Responding may change substantially over the course of a session
(McSweeney, Hinson, & Cannon, 1996). The role of satiation in
this effect was investigated in three experiments. Experiment 1
showed that the capacity of pigeons to consume milo over a 1-hr
period was relatively stable across three different methods of
measurement. In Experiment 2, pigeons were divided into two
groups that differed in their capacity based on one of those
measures. Key pecking was then reinforced under a
variable-interval 30-s schedule with hopper durations of 2 or 5
s. According to the satiation hypothesis, subjects with small
capacities should satiate faster and therefore show greater
decreases in food-reinforced responding than would subjects with
larger capacities. The results confirmed this prediction and
showed that the magnitudes of within-session decreases were
better predicted by the amount an animal consumed relative to its
capacity than by absolute amount alone. In Experiment 3, each
pigeon was prefed 0, 5, 15, or 25 g of milo prior to each
session. Consistent with the satiation hypothesis, increases
in prefeeding produced lower overall response rates in the
smaller capacity subjects than in the larger capacity subjects at
each level of prefeeding. These experiments demonstrate the
importance of a new variable in the control of behavior, and
provide a recommended technique for its measurement.
Key words: arousal, crop capacity, satiation, within-session
responding, key peck, pigeons